Page 3, Cardiac Cycle, Dr. D. Penney


The cardiac cycle examined in Figure 1.02 has been divided into 6 phases by alternate stipled and white areas. The letters at the top indicate phases identical to those seen in Figure 1.01.

AC = Atrial Contraction (Systole) (Phase 1)
IVC = Isovolumic Ventricular Contraction (Systole) (Phase 2)
Ejection = Ventricular Ejection (Phase 3)
IVR = Isovolumic Ventricular Relaxation (Diastole ) (Phase 4)
RF = Rapid Ventricular Filling (Phase 5)
Diastasis = Diastasis ("resting phase") (Phase 6)

The lower case letters on the left heart pressure curve correspond to waves appearing in the venous pulse.

a= a wave (caused by contraction of atrium)
c= c wave (caused by contraction of the ventricles)
x= x descent (caused by pulling of contracted right ventricle on tricuspid valve)
v= v wave (caused by venous return filling the large veins)
y= y descent (caused by blood flowing into the right atrium



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